Chevrolet Repair/timing chain

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Expert: TOM SHEETS - 8/9/2013

QuestionQUESTION: hi, i have a 06 cobalt with 2.2 over 100k, which lead up to no start condition one fine day, prior to which i had check engine light and rough idle and reduced engine power message, next time i went to start, two cranks and no start; so turns out timing chain has too much slack and likely timing is off enough to cause no start, so anyway at this point with valve cover off no damage to anything so far..so what might be best and economical way to salvage this engine...? get complete timing chain job done and if valve(s) have some minor damage that occurred during start up attempt and to just replace valve(s) with timing parts, or entire upper head along with timing job, or do a complete rebuild (overhaul)on the engine with a master engine rebuild, or swap with used junkyard engine all together? if you could break down the scenario individually and typical cost(s) associated with each? i realize that majority of cost is involved in labor, but still wondering what might make the best sense and value. thanks

ANSWER: HI JR, THIS HAS THE ECO TECH. YOU WILL NOT SEE ANY DAMAGE REMOVING THE VALVE COVER. IF THERE IS DAMAGE IT WILL BE ON THE VALVE SEATS [VALVE FACE WILL BE BENT] MORE THEN LIKELY THE CHAIN TENSIONER WENT SOUTH. THIS CREATED A LOT OF PLAY IN THE CHAIN..MORE THEN LIKELY IT BENT THE VALVES WHEN IT LET GO..SOUNDS LIKE YOU KNOW ABOUT THIS...IF YOU ARE GOING TO DO THE WORK YOURSELF I WOULD DO A CYLINDER LEAK DOWN TEST AND HOPE THAT MAYBE THE VALVES ARE OK 50 -50 SHOT. IF THEY ARE OK.. TEAR THE FRONT HALF OF THE ENG APART INSTALL NEW CHAIN, WATER PUMP AND TENSIONERS YOU COULD DO THIS FOR ABOUT $400.00. A SHOP WOULD CHARGE YOU ABOUT $1400.00. IF THE VALVES ARE BENT AND YOU DO THE WORK AS ABOVE PLUS VALVE JOB $800.00 TO $900.00 IF A SHOP DOES IT $2500.00. I DO NOT KNOW IF YOU COULD FIND ONE OF THESE ENGINES IN A BONE YARD. BUT I WOULD THINK ABOUT $1000.00 COMPLETE..THEY HAVE BEEN PRETTY MUCH TROUBLE FREE UNLESS YOU DO NOT CHANGE THE OIL IN THEM...I GUESS IF YOU COULD FIND A LOW MIL ENG AND YOU DID THIS YOURSELF THIS MAYBE THE BEST WAY OUT FOR YOU AND MAYBE THE BEST BET IF A SHOP DID IT FOR YOU AS WELL. YOU WILL NEED TO GET SOME PRICES FROM YOUR LOCAL BONE YARDS AROUND YOU AND CRUNCH SOME #'S..HOPE THIS HELPS YOU AND IF YOU NEED MORE INFO GET BACK TO ME.. GOOD LUCK TO YOU,,,TOM

---------- FOLLOW-UP ----------

QUESTION: hi again Tom, well great advice you gave. on hunch, i decided to take the valve cover off and inspect it carefully looking for any signs of damage, i did notice that on 1st cylinder (furthest away from timing chain) the intake valve lifter was cracked but rocker arm was just fine, i wonder if this is the tell-tail sign of valve hitting the piston upon cranking it and some damage possibly occurred? but no other evidence of anything irregular, i am still hopeful in doing a pressure/leak down test to tell if valves are ok. anything that tells you about the valve with lifter having damage to it, or anything else you might be able to tell from this?? thanks and appreciate any feedback you can offer.

AnswerHI JR,,WELL THIS IS UNUSUAL, A CRACKED LIFTER..I HAVE NOT SEEN THIS BEFORE..THIS COULD BE JUST A FLUKE THING, OR IT WAS LIKE THIS FOR A LONG TIME.. I WOULD JUST REPLACE THIS AND DO A LEAK DOWN TEST AND HOPE THAT ALL IS GOOD WITH THE VALVES...DID YOU EVER FIND OUT WHAT CAUSED THE TIMING CHAIN TO GO BAD..OR IS THAT WHAT YOU SAID [GOOD HUNCH ABOUT ????.]GOOD LUCK TO YOU AND LET MEK NOW HOW IT GOES...TOM

TOM SHEETS

Expertise

PLEASE READ ALL OF THIS BEFORE ASKING ANY QUESTIONS. IF THIS CHEVY SECTION IS MAXED OUT.YOU CAN REACH ME IN THE OLDS/BUICK SECTION. Will answer questions from 6:00am to 10:00pm all days [EST][[[ NO DIESEL OR PAINT QUESTIONS]]] will answer all 1965 to present QUESTIONS ON ALL GM'S on mechanics of these cars. Keep in mind i am not there in person i am going on what you are telling me !! PLEASE IF ASKING A QUESTION GIVE ME AS MUCH INFO AS POSSIBLE. THE MORE THE BETTER. SUCH AS YEAR,MAKE,MODEL,ENGINE SIZE. THIS WILL HELP ME HELP YOU. I will not be able to answer all questions because of some situations that i would really need to be there and see things for myself,such as electrical issues. In many cases i would need wiring diagrams. I can also give you an estimate on what the cost would be at our repair shop as an idea to help you. Keep in mind that my answer is ONLY MY ADVICE,ck with your mechanic as well.. >> THANK YOU, TOM..

Experience

I have been a ASE certified master mechanic for over 30 years and certified IN ALL 8 CATEGORIES,[engine repair,engine performance,auto trans,manual trans,clutches,steering and suspension,brakes,electrical systems,heating and air/cond. I am also a state CERTIFIED inspector for over 30 years. I do computer work [pcm]fault codes,pcm flashing,state inspection monitor readiness,repairs on exhaust,fuel service,[injection and carburetor,] charging system problems, running issues,alignments,frame problems,tire balance,struts and of course standard and anti-lock brakes.

Organizationsnys state auto repair industry and ase group.

PublicationsN/A

Education/Credentialshigh school,4 years of tech school,and many many hours of auto training with many gm classes and aftermarket training classes..